The present invention relates to a solid catalyst component for olefin polymerization and a catalyst comprising the component for olefin polymerization, which are used in homo- or co-polymerization of xcex1-olefins to give homopolymers or copolymers, and to a method for producing olefin polymers.
A variety of solid catalyst components comprising, as the indispensable ingredients, magnesium, titanium, halogen and electron donor have heretofore been proposed for catalysts. It is well known that the catalysts comprising the component of that type have high catalytic activity in olefin polymerization and that xcex1-olefin polymers produced in the presence of the catalyst have high stereospecificity. In particular, it is known that the solid catalyst components comprising, as the electron donor, an aromatic ester such as typically a phthalate exhibit excellent capabilities. However, using aromatic compounds is often disliked as being not safe and not good for the health.
Regarding non-aromatic electron donors, a method of using an electron donor of a malonate derivative has been reported. For example, in Japanese Patent Publication (JP-B) Hei-4-80044, proposed were compounds of a general formula (II): 
wherein either one or both of R4 and R5 are linear or branched hydrocarbon residues having 4 carbon atoms, or aromatic hydrocarbon residues. However, the stereospecificity of the polymers to be produced in the method in which the proposed compound is used is not good. In Japanese Patent Application Laid-Open (JP-A) Hei-6-122716, proposed are compounds of formula (II) in which R4 and R5 are bonded to each other to form a ring. In JP-A Hei-279517, proposed were compounds of formula (II) in which R4 and R5 are both hydrogens, those in which either one of R4 and R5 is a linear or branched hydrocarbon residue having 1 or more carbon atoms or an aromatic hydrocarbon residue, and the other is a hydrogen atom, and those in which R4 and R5 are both linear hydrocarbon residues having 2 or more carbon atoms. In the method in which the proposed compound is used, however, the yield of the polymers produced is extremely low. In JP-A Hei-8-157521, proposed were compounds of formula (II) in which R4 and R5 are both branched or cyclic hydrocarbon residues having 3 or more carbon atoms. In the method, however, the proposed malonates having branched or cyclic hydrocarbon residues are difficult to produce, and the yield of the polymers produced is low. Therefore, the method is not practicable. Other methods of using electron donors of other non-aromatic diesters were reported in JP-A Hei-3-124705 and JP-A Hei-3-168208. However, these methods are not always satisfactory for obtaining stereospecific polymers at high yields.
The object of the present invention is to provide a solid catalyst component for olefin polymerization and a catalyst comprising the component for olefin polymerization, in which the electron donor is free from the problem of lacking in safety and sanitation, and is inexpensive and easy to produce, and which exhibit high activity in producing olefin polymers with high stereospecificity, and also to provide a method for producing olefin polymers.
We, the present inventors have assiduously studied in order to attain the object noted above, and, as a result, have found that the problems mentioned above can be solved by the use of a solid catalyst component for olefin polymerization which comprises titanium, magnesium and an electron donor of a compound of the following general formula (I). On the basis of this finding, we have completed the invention.
Specifically, the invention provides a solid catalyst component for olefin polymerization, a catalyst for olefin polymerization, and a method for producing olefin polymers, which are as follows:
(1) A solid catalyst component for olefin polymerization, which comprises titanium, magnesium and a compound of a general formula (I): 
xe2x80x83wherein R1 and R2 each represent a linear or branched hydrocarbon residue having from 1 to 20 carbon atoms, and these may be the same or different ones; R3 represents an alicyclic hydrocarbon residue having from 3 to 20 carbon atoms; and n represents an integer of from 1 to 10.
(2) A catalyst for olefin polymerization, which comprises (A) a solid catalyst component for olefin polymerization of (1), and (B) an organic aluminium compound.
(3) A catalyst for olefin polymerization, which comprises (A) a solid catalyst component for olefin polymerization of (1), (B) an organic aluminium compound, and (C) a third component of an electron donor compound.
(4) The catalyst for olefin polymerization of (3), wherein the third component of an electron donor compound (C) is an organic silicon compound.
(5) A method for producing olefin polymers, which comprises polymerizing olefins in the presence of a catalyst for olefin polymerization of any one of (2) to (4).